A system for facilitating sender-side granular congestion control is provided. During operation, the first and second processes of an application can run on sender and receiver nodes, respectively. A first buffer on the sender node can be allocated to the first process. For the first process, the system can then identify a second buffer at a last-hop switch of the receiver node. The system can determine, based on in-flight packets, the utilization of the second buffer. The system can also determine a fraction of available space in the second buffer for packets from the first buffer based on the utilization. Subsequently, the system can determine whether the fraction of the available space can accommodate the next packet from the first buffer. If the fraction of the available space can accommodate the next packet, the system can allow the first process to send the next packet to the second process.